The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
An electric-powered machine transforms electric power to mechanical torque by inducing rotating magnetic fields with a field coil between a static element, i.e., a stator, and a rotatable element, i.e., a rotor. The rotating magnetic fields impose a torque upon the rotor. The torque is transferred to a shaft coupled to the rotor through conductor bars. The field coil may be associated with the stator.
Known electric-powered machines include a rotor having a stack of steel sheets assembled onto a rotatable shaft, and a plurality of conductor bars fabricated from conductive material, e.g., copper or aluminum. The conductor bars are preferably connected at both axial ends of the rotors using shorting end rings. Known field coils induce current flows through the conductor bars on the rotor that are preferably parallel to an axis of rotation of the rotor.
A known stator includes field coils for carrying a supply current to induce the magnetic field. The quantity of field coils may be varied and are preferably arranged in pairs. The most common types of electric machines are driven with single-phase or three-phase electrical power. A single-phase electric machine requires a starter to begin rotating the rotor as the magnetic field does not rotate. A three-phase electric machine rotates the rotor without a starter by sequentially rotating the magnetic field between the phases of the field coils.
Known field coils are wire-wound or bar-wound. A wire wound field coil is created from bundles of small diameter electrically conductive wires that are inserted into the stator. A bar-wound field coil is created from a series of bars of electrically conductive material that are inserted into the stator.